Wheel suspension for a pair of driven vehicle wheels

ABSTRACT

Wheel suspension for a pair of driven motor vehicle wheels, comprising a member (1), which consists of two cast aluminum member elements (2, 3) which are joined to each other. The member is intended to be fixed to a vehicle undercarriage. A wheel carrier (15) for each wheel is carried by the member via an upper and a lower link arm (12, 13), a slotted rod (14) and a longitudinal bar (18). A final drive unit (4) is fixed to the member together with a transverse leaf spring (30), which forms the wheel spring system, without the use of any special through-fasteners.

BACKGROUND OF THE INVENTION

The present invention relates to a wheel suspension for a pair of drivenmotor vehicle wheels, comprising a member intended to be fixed to avehicle undercarriage, for each wheel an upper and a lower link armpivotally joined to a wheel carrier, a longitudinal bar pivotallyconnectable to the vehicle undercarriage and pivotally connected to thewheel carrier, a slotted rod pivotally joined to the member and to therespective wheel carrier, spring means acting between the respectivewheel carrier and the member, shock absorbers and an anti-roll bar, adifferential carried by the member, and a pair of wheel axles driven bythe differential transmission, said axles each being joined to anindividual wheel hub mounted in the respective wheel carrier.

DESCRIPTION OF THE RELATED ART

SE-A-458 514, for example, describes a wheel suspension of the typedescribed by way of introduction, which provides high comfort and goodroad properties in the vehicle by, among other things, achievingstabilization and equalization of forces affecting the rear wheels, inorder to avoid undesired steering of the rear wheels. Furthermore, theknown wheel suspension provides a relatively large amount of space forvarious installations in the area around the rear wheels.

The wheel suspension known by SE-A-458 514 has a member system comprisedof a plurality of pressed sheet metal parts which are welded together.In order to compensate for unavoidable tolerance deviations, the lowerlink arm and the slotted rod are fixed to the member by means of boltswith excentric bushings, so that the correct camber angle and toe-in ofthe wheels can be adjusted after mounting.

The differential is screwed securely to the member. The longitudinalarms act as supporting arms for the wheel spring system and helicalsprings arranged concentrically therewith, said springs resting againstseats on the tops of the supporting arms. An anti-roll bar is joined tothe member on the rear side of the member via links with caps screwedsecurely over the rubber bushings, which grip over the anti-roll bar.

SUMMARY OF THE INVENTION

The purpose of the present invention is to achieve a wheel suspension ofthe type described by way of introduction, which, while retaining thepositive features of the known wheel suspension described above asregards comfort and ride can be manufactured at lower cost and be madelighter.

This is achieved according to the invention by virtue of the fact thatthe member comprises an upper and a lower member element, said elementsbeing screwed securely to each other and fixing the differential betweenthem via elastic damping elements.

A cast aluminum member system can be manufactured with much closertolerances than the previously known system consisting of pressed sheetmetal components which are welded together. This also means that thelink arm and the slotted rod can be joined to the member by means ofscrew fasteners which are free of play, e.g. serration screws, sinceafter-adjustment will no longer be needed. By clamping the differentialbetween the upper and lower member elements, simple assembly isachieved. No through-fixing elements are required to keep thedifferential in place, only screw fasteners which hold the memberelements together.

In a wheel suspension of the type described by way of introduction, byreplacing, in accordance with the invention, the conventional helicalsprings of the suspension with a transverse leaf spring, which has acentral portion securely fixed to the member and end portions actingagainst a top side of each lower link arm, it is possible to achieve adesign which saves weight and space. By virtue of the fact that thelongitudinal bars no longer need to serve as supporting arms for thewheel springs but are primarily bars for fixing the wheel carrier in thelongitudinal direction of the vehicle, their design can be simplifiedand their dimensions be reduced.

The free space in front of the member between the longitudinal bars canbe used with advantage for a U-shaped curved anti-roll bar, which isjoined to each longitudinal bar and to the member, the connectionbetween the longitudinal bars lying approximately midway between theends of each bar. Such a design provides better efficiency for theanti-roll bar than does the previously known design with the anti-rollbar placed behind the member.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail with reference toexamples shown in the accompanying drawings, where FIG. 1 and 2 show twoexploded views of a preferred embodiment of a wheel suspension accordingto the invention, in two different states of assembly, and FIG. 3 showsthe wheel suspension of FIG. 1 and 2 after final assembly but beforebeing mounted in the vehicle.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The wheel suspension according to the invention is a direct furtherdevelopment of the wheel suspension shown in SE-A-458 514. The basicgeometry, function and properties are the same in the two wheelsuspensions and therefore will not be dealt with in more detail here.For a detailed description, reference is made to SE-A-458 514.

According to the invention, a rear axle member (FIG. 3) generallydesignated 1, comprises an upper member element 2 and a lower memberelement 3, which are made of chill-cast aluminum and are fixed to eachother by means of a screw fastener. Member elements 2,3 are cast withforward and rear seats for a final drive unit 4 (differential), of whichonly the front seats 5 and 6 are shown in more detail. When the memberelements 1 and 2 are screwed together, the final drive unit 4 is clampedbetween forward and rear blocks of elastic material, e.g. rubber, ofwhich only the forward blocks 7 and 8 are visible in the Figures.

The upper member element 2 is cast with two forward arms 9 and two reararms 10, in the ends of which there are elastic bushings 11 in bores.Via screws through the bushings 11, the rear axle member 1 is screwedsecurely to the undercarriage of the vehicle. In the upper memberelement 2, an upper link arm 12 is pivotally mounted. A lower link arm13 is pivotally mounted in the lower member element 3 as is a slottedrod 14. The link arms 12,13 and the slotted rod 14 have distal ends,which are pivotally mounted in the wheel carrier 15, in which a wheelhub 16 is rotatably mounted. Said wheel hub 16 is drivingly connectedvia splines to a drive shaft 17 driven by the final drive unit 4. Thewheel carrier 15 is pivotally joined to one end of a longitudinal bar 18(FIG. 2 and 3), the other end of which is pivotally mounted in a bracket19 which is intended to be screwed securely to the undercarriage of thevehicle.

Completely cylindrical tubes are used as starting blanks for thelongitudinal bars 18, which are mandrelled, flattened and bended in aplurality of planes to the shape shown in the Figures. The lower end ofa shock absorber 20 is mounted on a pin 21 fixed to the bar 18. Theupper end is intended to be fixed in a conventional manner to theundercarriage of the vehicle. A bushing sleeve 22 is fixed in athrough-bore in the bar 18. Said sleeve houses a rubber bushing 23 withan inner bushing sleeve for fixing the ends of a U-shaped anti-roll bar24 in each longitudinal bar 18. Rubber bushings 25 are vulcanized ontothe anti-roll bar 24 and sleeves 26 are forced thereon. Each sleeve 26is made in one piece with an associated link 27, for example, in ahigh-strength plastic material, such as nylon. As is particularlyevident from FIG. 2, the mounting point of the anti-roll bar 24 in thelongitudinal bar 18 is approximately midway between the ends of said bar18. This makes the anti-roll bar highly efficient. The integrated designof the anti-roll bar 24 and the links 27 together with the bushings22,23 in through-holes in the longitudinal bars 18 provides a simple,reliable and easily assembled design.

Instead of a conventional wheel suspension system with a pair of helicalsprings arranged concentrically with the shock absorbers, the wheelsuspension according to the invention has a transverse wave-shapedpreformed leaf spring 30, which is common to the two wheels. The leafspring 30 has a central portion or a midportion 31. The leaf spring 30may consist of fiberglass reinforced epoxy plastic. Caps 32, which arescrewed securely to the lower member element 3 and which carryshear-soft rubber blocks 33 vulcanized thereto, fix the midportion 31 tothe member element 3. At its ends, the leaf spring 30 is in contact withits underside against rubber blocks 34, which are held in seats 35 atthe top of the outer end of each lower link arm 13. The spring 30 thuspasses below the final drive unit 4 and is fixed so that the spacebetween the final drive unit 4 and the ground-free-passage line isminimized. The spring 30 lacks, as does the final drive unit 4, fixingelements which pass through them. The rubber blocks 33 of the caps 32are intended, when the wheels are pushed far up, to be compressed andpermit a certain amount of movement of adjacent spring portions upwards,thus contributing to reducing the downward deflection of the centerportion 31 of the spring.

All of the mountings and joints described above are elastic and thuslack surfaces which slide against each other. The wheel suspensionrequires, in principle, no maintenance, and the only components whichrequire replacement during the life of the vehicle are the shockabsorbers.

We claim:
 1. Wheel suspension for a pair of driven motor vehicle wheels,comprising a member intended to be fixed to a vehicle undercarriage, foreach wheel an upper and a lower link arm pivotally joined to a wheelcarrier, a longitudinal bar pivotally connectable to the vehicleundercarriage and pivotally connected to the wheel carrier, a slottedrod pivotally joined to the member and to the respective wheel carrier,spring means for providing compression and extension acting between therespective wheel carrier and the member, shock absorbers and ananti-roll bar, a differential carried by the member, and a pair of wheelaxles driven by the differential, said axles each being joined to anindividual wheel hub mounted in the respective wheel carrier, whereinthe member comprises an upper and a lower cast aluminum member element(2,3), said elements being screwed securely to each other and fixing thedifferential (4) between them via elastic damping elements (7,8). 2.Wheel suspension according to claim 1, wherein the spring means areformed of a transverse leaf spring (30), which has a central portion(31) securely fixed to the member (1), and end portions acting against atop side (35) of each lower link arm (13).
 3. Wheel suspension accordingto claim 2, wherein the leaf spring (30) consists of fiberglassreinforced epoxy plastic.
 4. Wheel suspension according to claim 2,wherein the central portion (31) of the leaf spring (30) has an uppersurface in contact with at least one pair of spaced elastic dampingelements (33), which, when compressed during the upward resilientmovement of the wheels, permits a certain displacement upwards of theportions of the spring abutting against the damping elements, to reduce,during the resilient movement, the deflection downwards of the springportion located between the damping elements.
 5. Wheel suspensionaccording to claim 1, wherein said anti-roll bar is U-shaped and curved,and is joined to each longitudinal bar (18) and to the member (1), theconnection to each longitudinal bar lying approximately midway betweenthe two ends of said longitudinal bar.
 6. Wheel suspension according toclaim 5, wherein the anti-roll bar (24) is joined to the upper memberelement (2) via a pair of vertical links (27), each of said verticallinks having at a lower end, an integral sleeve (26), each of saidintegral sleeves being forced over a bushing (25) of elastic materialadhesively fixed to the anti-roll bar.
 7. Wheel suspension according toclaim 6, wherein the bushings (25) of elastic material are rubberbushings securely vulcanized to the anti-roll bar (24).
 8. Wheelsuspension according to claim 5, wherein each of the shock absorbers(20) are fixed in one of said longitudinal bars (18) at a point which islocated between the point of attachment of the anti-roll bar (24) to thesaid one longitudinal bar and the wheel carrier (15).
 9. Wheelsuspension for a pair of driven motor vehicle wheels, comprising amember designed to be fixed to a vehicle undercarriage, for each wheelan upper and a lower link arm pivotally joined to the member and to awheel carrier, a longitudinal bar pivotally connectable to the vehicleundercarriage and to the respective wheel carrier, a slotted rodpivotally joined to the member and to the respective wheel carrier,spring means for providing compression and extension between therespective wheel carrier and the member, shock absorbers and ananti-roll bar acting between the respective wheel carrier and themember, a differential carried by the member, and a pair of wheel axlesdriven by the differential and which are joined to individual wheel hubsmounted in respective wheel carriers, wherein the spring means areformed by a transverse leaf spring (30), which has a central portion(31) securely fixed to the member (1), and end portions acting against atop side (35) of each lower link arm (13).
 10. Wheel suspensionaccording to claim 9, wherein the leaf spring (30) consists offiberglass reinforced epoxy plastic.
 11. Wheel suspension according toclaim 9, wherein the central portion (31) of the leaf spring (30) has atop side in contact with at least a pair of spaced elastic dampingelements (33) which, during compression as the wheels move resilientlyupwards, permit a certain displacement upwards of the portions of thespring in contact with the damping elements in order to reduce, duringthe resilient movement, the deflection downwards of the spring portionbetween the damping elements.
 12. Wheel suspension according to claim11, wherein the end portions of the leaf spring (30) act against the topsides (35) of the lower link arms (13) via elastic damping elements(34).
 13. Wheel suspension for a pair of driven motor vehicle wheels,comprising a member intended to be fixed to a vehicle undercarriage, foreach wheel upper and lower link arms pivotally joined to a wheelcarrier, a longitudinal bar pivotally connected to the vehicleundercarriage and pivotally connected to the respective wheel carrier, aslotted rod pivotally connected to the member and to the respectivewheel carrier, spring means for providing compression and extensionbetween the respective wheel carrier and the member, shock absorbers andan anti-roll bar acting between the respective wheel carrier and themember, a differential carried by the member, and a pair of wheel axlesdriven by the differential, said wheel axles being joined to individualwheel hubs mounted in respective wheel carriers, wherein the anti-rollbar (24) is U-shaped and curved, and is joined to each longitudinal bar(18) and to the member (1), the connection to the respectivelongitudinal bar being approximately midway between the two ends of therespective longitudinal bar.
 14. Wheel suspension according to claim 13,wherein the anti-roll bar (24) is joined to the member via a pair ofvertical links (27), each having at a lower end an integral sleeve whichis forced over a bushing (25) of elastic material adhesively fixed tothe anti-roll bar.